/Engine/Source/Editor/UnrealEd/Public/EditorViewportLayoutThreePanes.h
[TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > MakeThreePanelWidget ( const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > & ViewportKey0, const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > & ViewportKey1, const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > & ViewportKey2, float PrimarySplitterPercentage, float SecondarySplitterPercentage )